Oil burner air control



Aug. 4, 1964 c. B. SMITHSONY 3,143,159

OIL BURNER AIR CONTROL Filed Oct. 1. 1962 lNVEIYTOR.

United States Patent 3,143,159 OIL BURNER AIR CONTROL Charles B.Smithson, Bloomington, 111., assignor to National Union ElectricCorporation, Stamford, Conn, a corporation of Delaware Filed Oct. 1,1962, Ser. No. 227,492 9 Claims. (Cl. 1581.5)

This invention relates to an oil burner air control and moreparticularly to control means for controlling the fiow of air throughthe blast tube of the burner.

One of the factors which affects the efliciency of an oil burner is theflow of air to the combustion zone of the burner. While many oil burnersheretofore advanced in clude means for controlling such airflow, many ofthese cause changes in the flame pattern of the burner because anadjustment of the air flow also necessitates adjustment of the positionof the burner nozzle relative to the air cone or blast tube outlet.Changes in the flame pattern are undesirable because the efficiency ofthe burner may be affected adversely. Moreover, many of the secondaryair flow control means currently in use are of a complex construction,which results in an increase in the cost of the burner.

Accordingly, it is a general object of the present invention to providea novel and improved control for the air flow through the blast tube ofan oil burner.

Another object is to provide a novel air flow control which is adaptedfor use with both low andhigh pressure type oil burners.

A more particular object is to provide a novel control means forcontrolling the air flow through the blast tube of an oil burner whichdoes not materially change the shape of the flame of the burner uponadjustment of the air flow.

These and other objects will become apparent upon making reference tothe detailed description which follows and accompanying sheets ofdrawings, in which:

FIG. 1 is a side-elevational view, with some parts in section andportions thereof broken away to show underlying parts, of the blast tubeof an oil burner employing an air flow control embodying the features ofthe present invention;

FIG. 2 is an enlarged plan view of a portion of the blast tube of FIG.12, with a portion of the tube removed to show underlying parts andtaken substantially along the line 22 of FIG. 1;

FIG. 3 is a vertical sectional view taken substantially along the line3-3 of FIG. 1; and

FIG. 4 is a vertical sectional view taken substantially along the line4-4 of FIG. 1, but with a portion of the structure removed.

Briefly described, the present invention contemplates an improved flowcontrol means for the air flow through the blast tube of an oil burner.Such control means is disposed in the blast tube of the burnerimmediately upstream of the fuel atomizing nozzle thereof and comprisesa centrally disposed axially fixed baffle in the blast tube and anaxially shiftable sleeve member having a portion engaging the inner wallof the blast tube, another portion engaging the periphery of the baffle,and an intermediate connecting portion. The baffle engaging portion isprovided with a plurality of circumferentially spaced axially extendingslots, the effective size of which may be varied upon movement of thesleeve member.

By reason of the foregoing construction, the air flow will be caused toconverge as it enters the sleeve member and thereafter to diverge orflow radially outwardly around the baffle toward a ring of whirl vanesand an air cone at the open end of the blast tube. Because of theforegoing location of the control means and the flow path taken by theair passing through and downstream there- 3,143,159 Patented Aug. 4,1964 of, a more positive control of the flow is obtained. In addition,adjustment of the control means to change the amount of air flow doesnot change the position of the atomizing nozzle relative to the end ofthe blast tube. Consequently, the shape of the flame pattern at thedischarge end of the blast tube is not changed to any material degree.Moreover, the air control can readily be used with blast tubes ofdifferent lengths.

In FIG. 1, a portion of a low pressure oil burner embodying the featuresof the present invention is illustrated. The oil burner includes acasing, the lower portion of which is indicated at 35, which serves as amounting for the main components of the burner. Thus, an electric motor(not shown) is mounted at one side of the upper portion of the casing,the motor being drivingly connected to a secondary air fan (not shown)mounted within the upper portion of the casing. The motor also drives acombination oil metering and primary air pump unit mounted on theopposite side of the upper portion of the casing. A portion of thecombination oil metering and primary air pump is indicated at 30 in FIG.1.

The pump unit 30 receives oil from a fuel tank, and a mixture of primaryair and oil under pressure is delivered to a diffusor 36 mounted in oneend of the lower casing portion 35. A pipe 37 connects the outlet of thepump unit 30 with the diffusor 36. In addition, the secondary air fandelivers a flow of secondary air to the lower casing portion 35 andthence through a blast tube 40 extending outwardly from the opposite endof the casing portion 35.

The frothy air-oil mixture obtained from the pump unit 30 is separatedinto its liquid and air phases in the diffusor 36. Liquid oil underpressure collecting in the bottom of the diffusor 36 is directed axiallythrough the blast tube 40 to an atomizing nozzle 38 by means of a pipe366 (FIG. 1), the nozzle 38 being disposed upstream of an air cone 44mounted on the remote end of the blast tube 40. Air under pressure abovethe level of the oil in the diffusor 36 is supplied to the atomizingnozzle 38 by means of another pipe 367. The separate oil and air flowsthrough the pipes 366 and 367 are recombined in the nozzle 38 to bethereafter discharged axially outwardly from a central orifice 368 (FIG.3) in the end of the nozzle.

In order to ignite the atomized oil-air mixture discharging from thenozzle 38, a starting electrode assembly 43 is provided. As will beapparent in FIGS. 1 and 3, the assembly 43 comprises a pair ofelectrodes 371 mounted in radially spaced axially extending insulators372 supported by a baffle 46 comprising a portion of a secondary airflow control means 400 to be hereinafter described. The terminal ends,indicated at 373, of the electrodes 371 are closely spaced adjacent theorifice 368 so as to permit a high voltage spark to be maintainedthereacross to ignite the atomized fuel-air mixture. Such spark isobtained from the secondary winding of a starting transformer (notshown), the potential being conducted to the electrodes 371 by a pair ofwires or cables 374. A spark is maintained across the terminals 373 fora predetermined period suflicient to ignite the mixture from the nozzle38, the spark thereafter being discontinued unless restarting isnecessary. A set screw 375 (FIG. 1) permits adjustment of the entirediffusor assembly relative to the housing portion 35 so as to regulatethe distance between the nozzle 38 and the outlet, indicated at 379, ofthe air cone 44. i

The air flow and flame pattern are controlled in part by a ring of vanes376 (FIGS. 1 and 4) disposed around the inner peripheral wall of theblast tube 40 adjacent the discharge end thereof and by a tapered endwall 380 on the air cone 44. Each vane 376 is provided with a pluralityof edge tabs or fingers 377 (FIGS. 1 and 4) which extend through slitsin the blast tube 40, and which are thereafter bent over into engagementwith the outer surface of the blast tube to retain the vanes inposition. As seen in FIG. 1, each vane 376 extends both forwardly andrearwardly of the nozzle orifice 368, and the forward ends of the vanes376 extend beyond the end of the blast tube 40 into the tapered portionof the cone 44 defined by the end wall 380 and terminate at or closelyadjacent the discharge opening 379 of the cone. The vanes 376 arearranged at suitable angles so as to impart a whirl to the secondary airflow through the blast tube. The angularly disposed vanes 376 and thetapered annular end wall 380 of the cone 44 divert the secondary airinto the atomized oil-air stream from the nozzle 38 whereby to obtainintimate penetration and mixing of the two streams and highly efficientcombustion. The mounting of the vanes 376 on the blast tube 40 ratherthan on the air cone 44 facilitates substitution of other cones havingdifferent outlet diameters.

Secondary air from the secondary air fan enters the inner or upstreamend, indicated at 378 (FIG. 1), of the blast tube 40. The secondary airflow thus proceeds through the blast tube and toward the secondary airflow control means 400 which serves to control the quantity anddirection of the secondary air flowing past the control 400 and throughthe vanes 376 and discharge opening 379 in the air cone 44.

As will be apparent from FIGS. 1 and 2, the secondary air flow controlmeans 400 comprises a shiftable sleeve member 47, the electrode andnozzle support disk or baflle 46, and a manually adjustable means 48 forshifting the sleeve member 47 relative to the baflle 46 and blast tube40.

As best shown in FIG. 2, the sleeve member 47 comprises a tubularupstream portion 401 engaging the inner surface of the blast tube 40, anintermediate conically tapered or connecting portion 402, and adownstream tubular portion 403 enclosing and peripherally engaging thebaflle 46. The baffle 46 is provided with an annular axially extendingflange 405 for supporting the tubular portion 403. The upstream portion401 is of relatively short axial extent, while the downstream portion403 has a substantial axial length permitting a substantial range ofmovement without disengagement from the baffle 46. The tubular portion403 is provided with a plurality of circumferentially spaced axiallyelongated openings or slots 404 therethrough, such openings extendingfor substantially the full length of the portion 403 and thus overlyingthe baffle 46 throughout the range of movement of the sleeve 47. A ringof smaller openings or apertures 406 is provided in the conical portion402, such openings 406 at all times remaining unobstructed.

The sleeve 47 is supported in the blast tube 40 by means of thewall-to-wall sliding engagement between the portion 401 and the innerwall of the tube 40, by the engagement between the inner wall of theportion 403 and the flange 405, and by a plurality of circumferentiallyspaced radially outwardly extending legs 407 secured to the outerperiphery of the portion 403 at the downstream end thereof, and alsoengaging the inner wall of the tube 40.

The manually adjustable means 48 for controlling the position of thesleeve 47 comprises, in this instance, an elongated bar or strap 411secured to the portions 401- 402 of the sleeve 47, the bar 411 extendingaxially upstream through the inlet end 378 of the blast tube 40 and intothe lower casing portion 35. The opposite or upstream end, indicated at412, of the bar 411 is bent at a right angle and is provided with athreaded opening for receiving the threaded shank of an elongatedadjusting screw 413. The screw 413 has an enlarged head 414 providedwith a slot to facilitate manipulation thereof, the remote inner end,indicated at 416, of the screw 413 being unthreaded and supported in anopening in the end of an upstream lug 417 formed in the casing portion35. Thus, manipulation of the screw 413 effects axial movement of thebar 411 and a shifting of the sleeve member 47. A spring 418 is providedbetween the screw head 414 and the adjacent end wall of the casingportion 35 to maintain the screw 413 in an adjusted position.

It will be apparent that the axial position of the sleeve 47 relative tothe bafile 46 determines the eflective area of the sleeve slots, sucharea being the summation of the open upstream portions, indicated at404a, of the slots 404 to the left of the bafile 46 as viewed in FIGS. 1and 2. Thus, axial shifting of the sleeve 47 in the blast tube 40 servesto enlarge or reduce the size of the upstream slot areas 404a therebyvarying the effective cross-sectional area of the blast tube withrespect to the secondary air flow.

Because of the configuration of the sleeve 47, air entering the inletend 378 of the blast tube and approaching the sleeve 47 will first becaused to converge toward the center of the tube because of the conicaltaper of the intermediate portion 402. As the secondary air flow entersthe portion 403 its direction is substantially axial, and then thebaffle 46 diverts the air flow radially outwardly through the open slotportions 404a toward the wall of the blast tube 40. Such convergence anddivergence of the flow is indicated by arrows in FIG. 1. After passingthrough the exposed slot portions 404a of the sleeve 47, the secondaryair flow continues axially through the blast tube until it reaches thevanes 376. As previously mentioned, the vanes 376 impart a whirl orvortex action to the flow which is directed through the opening 379 intothe atomized'air-oil stream discharging from the nozzle 38 by theannular inwardly tapering end Wall 380 of the air cone 44. The secondaryair flow is thus brought into intimate contact with unburned oilparticles, and other combustible products, to thereby insure highcombustion efliciency. Such efliciency results from the coaction betweenthe whirling secondary air fiow provided by the vanes 376, the annularinwardly tapering end wall 380, and the size of the opening 379. Forexample, with the blast tube and air control arrangement just described,it is possible to obtain a C0 content in the combustion gas of about12-14% as compared with the l012% normally considered to be a high levelof efficiency.

Moreover, with the foregoing construction, a generally spherical orball-shaped flame pattern is obtained throughout a wide range offuel-air delivery rates, as for example between a range of one-half totwo and one-quarter gallons of fuel per hour. This highly desirableresult is at-, tributable to the fact that the secondary air is notforced along the central axis of the blast tube, which would tend toproduce an elongated torch-like flame, and to the further fact that thespin-imparting vanes for the secondary air i.e. the angular vanes 376)are located solely at the blast tube outlet.

As previously noted, the ring of smaller holes 406 in the conicallytapered portion 402 of the sleeve 47 at all times remain open so thatregardless of the position of the sleeve, secondary air will never becompletely shut off. While the holes 406 are provided primarly to complywith certain safety requirements relating to oil burners, they alsocontribute to an over-all balancing of the secondary air flow and flamepattern. Another opening 408 in the baflle 46 also serves to balance theflow through and downstream of the control 400. v

The blast tube air control means 400 has been illustrated and describedin conjunction with a low pressure oil burner utilizing a mixture of oiland primary air and a diffusor so that the control 400 operates onsecondary air. However, it will be apparent that the same blast tube aircontrol arrangement is also usable in a high pressure oil burner whichdoes not employ a dilfusor or separate primary and secondary airsources. In such case, oil alone is supplied under pressure to thenozzle in the blast tube and the blast tube air control 400 regulatesthe sole supply of air to the blast tube.

Although the invention has been described with particular reference to acertain specific structural embodiment, it should be understood thatvarious modifications and equivalents may be resorted to withoutdeparting from the scope of the invention as defined in the appendedclaims.

I claim:

1. In an oil burner having a blast tube with a nozzle disposed centrallytherein, control means for regulating the flow of air through said blasttube, comprising a transverse centrally disposed baffle in fixedrelation in said blast tube and of smaller diameter than said blasttube, a shiftable sleeve member having a portion at the upstream side ofsaid bafiie slidably engaging the interior of said blast tube and aportion slidably engaging the periphery of said bafile, said last-namedportion having at least one opening therein, and means for moving saidshiftable member axially of said blast tube to vary the effective sizeof said opening at the upstream side of said bafl-le, whereby the flowof air passes axially through said sleeve member to said baflie, thenceradially outwardly through said opening, and thence axially between saidsleeve member and said blast tube.

2. The structure of claim 1, further characterized in that a pluralityof openings are provided in said bafiieengaging portion of said sleevemember, said openings comprising a plurality of circumferentially spacedaxially extending slots.

3. The structure of claim 2, further characterized in that said sleevemember includes a tapering portion connecting said blast tube-engagingand bathe-engaging portions, said tapering portion being effective tocause convergence of said air flow toward the portions of said slotsupstream of said bafiie.

4. In an oil burner including a blast tube and nozzle means fordischarging a fluid stream from said tube, the improved means forcontrolling a flow of air through said blast tube, comprising acentrally disposed transverse bafiie of lesser diameter than said tubeand rigidly secured centrally therein, said bafile providing a supportfor said nozzle means, a sleeve member mounted in said blast tube andhaving a portion slidably engaging the inner wall of said tube at theupstream side of said baflie, another portion slidably engaging theouter periphery of said baffle, and a portion connecting said blasttube-engaging and bathe-engaging portions, said baflle-engaging portionhaving a plurality of openings therein, and manually adjustable meansfor shifting said sleeve member to control the effective size of saidopenings at the upstream side of said baffie, said sleeve member andsaid bafile being eifective to cause convergence of said air flowupstream of said baflie and divergence of said flow radially outwardlythrough said openings and around said battle.

5. The flow control device of claim 4, further characterized in thatsaid blast tube and baflie are circular in cross section, said blasttube-engaging and baflle-engaging portions are cylindrical, and saidconnecting portion is conical.

6. The control device of claim 5, further characterized in that saidbafiie comprises a circular disk disposed transversely of the axis ofsaid blast tube, said disk having an annular axially extending flangetherearound for engaging and supporting said sleeve member.

7. The flow control of claim 4, further characterized in that said blasttube includes a plurality of vanes carried at the discharge end thereoffor imparting a whirl to said air flow.

8. The flow control of claim 7, further characterized in that an annularair cone is provided having a cylindrical mounting portion and anannular inwardly tapering outlet portion, said cylindrical mountingportion being fitted around the outside of said end of the blast tube,and said vanes are secured solely to said blast tube whereby to permitreplacement of the cone without disturbing the vanes.

9. In an oil burner having a blast tube and centrally disposed nozzlemeans, the improved means for controlling the flow of air through theblast tube comprising a disk-shaped baffle of lesser diameter than saidtube and mounted in fixed relation therein, said bafiie supporting saidnozzle means, a sleeve movably mounted in said blast tube, said sleevehaving an enlarged diameter portion slidably engaging the blast tubeupstream from said bafile and a reduced diameter portion spaced fromsaid blast tube and slidably engaging the periphery of said bafiie, saidreduced diameter sleeve portion having a plurality of circumferentiallyspaced openings, adjustable means for shifting said sleeve axially ofsaid blast tube to vary the size of said openings at the upstream sideof said bafiie, whereby air flows axially through said sleeve, radiallyoutwardly through the adjusted openings, and thence axially through thespace between said sleeve and said tube, said sleeve being free ofwhirl-imparting means, and a plurality of whirl-imparting vanes at thedischarge end of said blast tube downstream from said sleeve.

Kermode Aug. 8, 1916 Robb Feb. 5, 1963

1. IN AN OIL BURNER HAVING A BLAST TUBE WITH A NOZZLE DISPOSED CENTRALLYTHEREIN, CONTROL MEANS FOR REGULATING THE FLOW OF AIR THROUGH SAID BLASTTUBE, COMPRISING A TRANSVERSE CENTRALLY DISPOSED BAFFLE IN FIXEDRELATION IN SAID BLAST TUBE AND OF SMALLER DIAMETER THAN SAID BLASTTUBE, A SHIFTABLE SLEEVE MEMBER HAVING A PORTION AT THE UPSTREAM SIDE OFSAID BAFFLE SLIDABLY ENGAGING THE INTERIOR OF SAID BLAST TUBE AND APORTION SLIDABLY ENGAGING THE PERIPHERY OF SAID BAFFLE, SAID LAST-NAMEDPORTION HAVING AT LEAST ONE OPENING THEREIN, AND MEANS FOR MOVING SAIDSHIFTABLE MEMBER AXIALLY OF SAID BLAST TUBE TO VARY THE EFFECTIVE SIZEOF SAID OPENING AT THE UPSTREAM SIDE OF SAID BAFFLE, WHEREBY THE FLOW OFAIR PASSES AXIALLY THROUGH SAID SLEEVE MEMBER TO SAID BAFFLE, THENCERADIALLY OUTWARDLY THROUGH SAID OPENING, AND THENCE AXIALLY BETWEEN SAIDSLEEVE MEMBER AND SAID BLAST TUBE.